A/C Compressor - PeachParts Mercedes-Benz Forum

sailor15015 · #1 11-02-2005, 10:08 PM

Hey everyone. I know its the wrong season to be asking an a/c question but I've been reasearching this on this forum and other sites and its driving me crazy. I'm going on a trip next summer and I want to get it up and running over the winter. My car has been converted to r134a. A P/O had the compressor, dryer, exp valve, and fittings all replaced. I know I have a leak and something funky is going on with the compressor. I put a charge WITH OIL in it to get it working. The compressor works but it makes a god-aweful noise. Does it need to be replaced? If so is there a special compressor that this car uses when its been convereted? Will the original R4 compressor work if I can get my hands on one? I've read Dieselgiant's how-to on cleaning out the system and that's where I'm going to start. On my list of things to do is to replace the reciever/drier and the expansion valve. My main concern right now is the compressor. Any help/advice would be greatly appreciated.

tangofox007 · #2 11-02-2005, 10:35 PM

Quote:

Originally Posted by sailor15015

Hey everyone. I know its the wrong season to be asking an a/c question but I've been reasearching this on this forum and other sites and its driving me crazy. I'm going on a trip next summer and I want to get it up and running over the winter. My car has been converted to r134a. A P/O had the compressor, dryer, exp valve, and fittings all replaced. I know I have a leak and something funky is going on with the compressor. I put a charge WITH OIL in it to get it working. The compressor works but it makes a god-aweful noise. Does it need to be replaced? If so is there a special compressor that this car uses when its been convereted? Will the original R4 compressor work if I can get my hands on one? I've read Dieselgiant's how-to on cleaning out the system and that's where I'm going to start. On my list of things to do is to replace the reciever/drier and the expansion valve. My main concern right now is the compressor. Any help/advice would be greatly appreciated.

I converted my '82 300D to R-134a about six years ago. My compressor started making a lot of noise shortly thereafter. But it still works. So I am going to ride it till it quits, then convert back to R-12.

sailor15015 · #3 11-02-2005, 10:39 PM

I'm hoping when I open it up if I actually pour the proper oil in it that that will quiet the noise.

boneheaddoctor · #4 11-03-2005, 08:42 AM

Put too much oil in it and you risk slugging the compressor (equal to hydrolocking an engine)

#5 11-03-2005, 09:45 AM

BHD is absolutely right.

One of my favorite a/c quotes is from Steve Brotherton. He wrote: "Too much oil destroys compressors while not enough oil wears them out."

A noisy compressor always makes for a difficult question. Do you replace it or not. I have heard a few compressors that sounded like sirens but lasted for years. You just never know.

As far as replacing components, why are you replacing the TXV? Is it bad?

Good luck,

sailor15015 · #6 11-03-2005, 10:54 AM

Quote:

Originally Posted by LarryBible

As far as replacing components, why are you replacing the TXV? Is it bad?

Good luck,

By TXV do you mean expansion valve? I thought it got gummed up and should be replaced when the reciever/dryer is replaced. If it doesn't need to be that's just one less thing to buy/worry about. I have the reciept from when the car was converted and I know how much oil the shop put in when they converted it to r134a. If my compressor is bad will the original R4 compressor work with r134a? Synthetic oil, right?

#7 11-03-2005, 02:34 PM

sailor,

I've never seen a TXV (expansion valve) fail due to being gummed up. They are easily cleaned upon removal. The only two ways that I've ever seen them fail is that they start leaking between the diaphragm and the body, OR they open up wide providing no restriction for the system. That does not mean that they cannot fail any other way, it's just that it's all I've seen.

Yes lots of R4's have been used in conversions in the past, but now there is no longer a need to run 134 in these cars. 134 has gone up in price while R12 have taken a nose dive. I bought R12 a few months ago for $14.16 per pound while 134 has gone up near $10.

If you are going to open the system and replace the r/d anyway, simply flush everything good enough to get out most of the oil, put in 6 oz. of mineral oil or the R12 compatible synthetic and charge with R12. You will have a better performing and longer lived system.

I looked at your signature to see where you are before recommending reverse conversion. If you were in a cold climate it would not be as big of a problem running 134, but the time I spent in Norman I remember lots of heat.

Good luck,

Padraig · #8 11-03-2005, 05:29 PM

Quote:

Originally Posted by LarryBible

BHD is absolutely right.

One of my favorite a/c quotes is from Steve Brotherton. He wrote: "Too much oil destroys compressors while not enough oil wears them out."

A noisy compressor always makes for a difficult question. Do you replace it or not. I have heard a few compressors that sounded like sirens but lasted for years. You just never know.

As far as replacing components, why are you replacing the TXV? Is it bad?

Good luck,

A noisy compressor? or a a noisy clutch - which is it? How does one determine which?

#9 11-03-2005, 05:43 PM

I've said many times on this forum that noises and vibrations are very difficult to deal with over the internet. I would have to hear it.

That said, you need to listen to the noise with the clutch engaged and disengaged. What kind of noise is it? Is it squealing, whining, knocking?

If it is squealing with the clutch engaged then it could be a slipping clutch but that usually only happens when the compressor initially kicks in.

If it is a whining or knocking sound and it only happens when the clutch is engaged, then the problem is the compressor.

Again, difficult to know without being there.

Good luck,

Padraig · #10 11-03-2005, 06:35 PM

Quote:

Originally Posted by LarryBible

I've said many times on this forum that noises and vibrations are very difficult to deal with over the internet. I would have to hear it.

That said, you need to listen to the noise with the clutch engaged and disengaged. What kind of noise is it? Is it squealing, whining, knocking?

If it is squealing with the clutch engaged then it could be a slipping clutch but that usually only happens when the compressor initially kicks in.

If it is a whining or knocking sound and it only happens when the clutch is engaged, then the problem is the compressor.

Again, difficult to know without being there.

Good luck,

It's not squealing, sounds like a hell of noise. - like, clatter, clutter

sailor15015 · #11 11-03-2005, 07:28 PM

Larry,

Thanks for all of your help. You've got me seriously thinking of putting R-12 back in it now. The charging fittings, if that's what they're called, would be the wrong size, wouldn't they? How would I go about converting them back? Thanks a lot.

boneheaddoctor · #12 11-03-2005, 07:35 PM

Quote:

Originally Posted by Padraig

It's not squealing, sounds like a hell of noise. - like, clatter, clutter

you sure your belt doesn't have a chunk missing? My W116 made the most god aweful noise when that happened.....